What kind of seats? Rigid backs, tilt backs? PRP makes really nice rigid back seats.
I have these PRP Premier Highbacks going into my truck. as far as a harness is concerned you need something to mount the harness too, and the seats. Which usually means you need a bar that will run behind the seats to attach the harness to.
These are suspension seats, I got 2 All gray like the picture shipped to my house for 430 dollars. The seats are listed as 220 each but I know a couple vendors from another board that can get you good deals.